This invention relates to a magnetically actuated switch gauge and associated circuitry, for controlling other circuits, i.e., act as a circuit breaker to stop or start devices in response to a sensed condition such as temperature, pressure, liquid levels, speed (rpm, mph, etc.) or electrical properties. Typically such condition responsive switch gauges will act to shut down or start equipment, engines or motors, or provide audible or visual signals when a predetermined condition has been reached.
Typical prior signalling and switch gauges can be found in U.S. Pat. Nos. 3,586,799; 4,021,627; and 3,578,931. The concept of magnetically actuated and/or "Hall effect" type switch gauges can be found in U.S. Pat. Nos. 4,957,687 and 5,121,109. Various gauges of this type have been sold under the mark SWICHGAGE.RTM. by Frank W. Murphy Mfr., Inc.